JP2009247109A - Flexible actuator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To shorten axial dimensions of a flexible actuator detecting the stroke position of an output rod for the flexible actuator with a stroke sensor, while eliminating need for complex computation processings. <P>SOLUTION: The rotational angle of a male screw member 95 of a feed screw mechanism 39, formed by the male screw member 95 and a female screw member 96 which are screwed with each other, is set to less than 360°. The stroke sensor 102, which detects the stroke position of the output rod 33, detects the stroke position of the output rod 33, based on the rotational angle of the male screw member 95 which is detected by a detected portion 104 and a detecting portion 105. It is thus possible to facilitate calculation processing without the need for calculating the rotational speed of the male screw member 95, and it is also possible to reduce the axial dimensions of the flexible actuator 14, by shortening the axial dimensions of the detecting portion 105, as compared with an actuator where the detecting portion 105 at a housing 32 detects the position of the detected portion 104 provided at the output rod 33. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention includes a feed screw mechanism including a first screw member and a second screw member that are screwed together, the first screw member is connected to a rotation shaft of a motor, and the second screw member is connected to an output rod. The present invention also relates to a telescopic actuator for detecting a stroke position of the output rod by a rotation of a rotation shaft of the motor by a stroke sensor.

In a telescopic actuator that converts the rotation of an electric motor into a telescopic motion of an output rod using a ball screw mechanism, the stroke position of the output rod is detected by detecting the rotation angle of the output rod with a resolver. It is known.
JP 2007-187262 A

  By the way, in the above-mentioned conventional one, the female screw member of the ball screw mechanism rotates over 360 ° while the output rod moves from the contracted side limit position to the extended side limit position. There is a problem that it is necessary to calculate the rotation speed of the member, and the calculation processing for detecting the stroke position of the output rod is complicated.

  In order to avoid this, it is conceivable that the detected part provided on the output rod is directly detected by the detecting part provided on the housing. However, in this case, at least the axial dimension of the detected part is moved. It is necessary to make the distance equal, and there is a problem that the axial dimension of the telescopic actuator increases due to the increase in the size of the detection unit.

  The present invention has been made in view of the above circumstances, and in the case where the stroke position of the output rod of the telescopic actuator is detected by a stroke sensor, the axial dimension of the telescopic actuator is shortened without the need for complicated calculation processing. With the goal.

  In order to achieve the above object, according to the first aspect of the present invention, a feed screw mechanism comprising a first screw member and a second screw member that are screwed together is provided, and the first screw member is mounted on the motor. In a telescopic actuator that is connected to a rotary shaft, connects the second screw member to an output rod, and detects a stroke position of the output rod by rotation of the rotary shaft of the motor by a stroke sensor, a rotation angle of the first screw member Is set to be less than 360 degrees, and the stroke sensor detects the stroke position of the output rod based on the rotation angle of the first screw member.

  According to a second aspect of the present invention, in addition to the structure of the first aspect, the first screw member includes a thrust receiving flange that transmits axial thrust force to the housing, and the stroke sensor includes the thrust sensor. A telescopic actuator is proposed that includes a detected portion provided on an outer periphery of a receiving flange, and a detecting portion provided on the housing and facing the detected portion.

  The second housing 32 of the embodiment corresponds to the housing of the present invention, and the male screw member 95 and the female screw member 96 of the embodiment correspond to the first screw member and the second screw member of the present invention, respectively.

  According to the configuration of the first aspect, the rotation angle of the first screw member of the feed screw mechanism including the first screw member and the second screw member that are screwed to each other is set to less than 360 °, and the stroke position of the output rod is set. Since the detecting stroke sensor detects the stroke position of the output rod based on the rotation angle of the first screw member, it is not necessary to calculate the number of rotations of the first screw member, which not only simplifies the calculation process but also outputs. The axial dimension of the expansion / contraction actuator can be reduced by shortening the axial dimension of the detection section as compared with the detection of the position of the detected section provided on the rod by the detection section provided on the housing.

  According to the second aspect of the present invention, the stroke sensor includes the detected portion provided on the outer periphery of the thrust receiving flange that transmits the axial thrust force of the first screw member to the housing, and the detected portion provided on the housing. Since it comprises the detection part which opposes a part, it can arrange | position a to-be-detected part and a detection part inside and outside radial direction, and can further shorten the axial direction dimension of an expansion-contraction actuator.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  1 to 6 show an embodiment of the present invention. FIG. 1 is a perspective view of a left rear wheel suspension device, FIG. 2 is a view in the direction of the arrow 2 in FIG. 1, and FIG. 3 is an enlarged cross-sectional view of FIG. 3, FIG. 4 is an enlarged view of 4 parts in FIG. 3, FIG. 5 is an enlarged view of 5 parts in FIG. 3, and FIG.

  As shown in FIGS. 1 and 2, a double wishbone type rear suspension S for a four-wheel steering vehicle includes a knuckle 11 that rotatably supports a rear wheel W, and an upper that connects the knuckle 11 to a vehicle body so as to be movable up and down. The arm 12 and the lower arm 13, a toe control actuator 14 for connecting the knuckle 11 and the vehicle body to control the toe angle of the rear wheel W, a damper 15 with a suspension spring for buffering the vertical movement of the rear wheel W, and the like.

  The distal ends of the upper arm 12 and the lower arm 13 whose base ends are connected to the vehicle body by rubber bush joints 16 and 17, respectively, are connected to the upper and lower portions of the knuckle 11 via ball joints 18 and 19, respectively. The toe control actuator 14 has a proximal end connected to the vehicle body via a rubber bush joint 20 and a distal end connected to the rear portion of the knuckle 11 via a rubber bush joint 21. The lower end of the suspension spring-equipped damper 15 whose upper end is fixed to the vehicle body (upper wall 22 of the suspension tower) is connected to the upper portion of the knuckle 11 via the rubber bush joint 23.

  When the toe control actuator 14 is driven to extend, the rear portion of the knuckle 11 is pushed outward in the vehicle width direction, the toe angle of the rear wheel W changes in the toe-in direction, and when the toe control actuator 14 is driven to contract, the rear portion of the knuckle 11 is Pulled inward in the width direction, the toe angle of the rear wheel W changes in the toe-out direction. Therefore, in addition to normal steering of the front wheels by operating the steering wheel, by controlling the toe angle of the rear wheel W according to the vehicle speed and the steering angle of the steering wheel, the straight running stability performance and turning performance of the vehicle can be improved. it can.

  Next, the structure of the toe control actuator 14 will be described in detail with reference to FIGS.

  As shown in FIGS. 3 and 4, the toe control actuator 14 includes a first housing 31 integrally provided with a rubber bush joint 20 connected to the vehicle body side, and a rubber bush joint 21 connected to the knuckle 11 side. And a second housing 32 that supports the integrally provided output rod 33 so that the output rod 33 can extend and contract. The opposing portions of the first and second housings 31 and 32 are in a state where they are inlay-fitted through a seal member 34. The coupling flanges 31a and 32a are integrated by fastening with a plurality of bolts 35. A motor 36 with a brush as a driving source is housed in the first housing 31, and a planetary gear type reduction gear 37, an elastic coupling 38, and a trapezoidal screw are used in the second housing 32. The feed screw mechanism 39 is housed.

  The outer shell of the motor 36 includes a yoke 40 having a flange 40a and formed in a cup shape, and a bearing holder 42 fastened to the flange 40a of the yoke 40 with a plurality of bolts 41. Bolts 41 for fastening the yoke 40 and the bearing holder 42 are screwed into the end face of the first housing 31, and the motor 36 is fixed to the first housing 31 using the bolts 41.

  The rotor 44 disposed in the annular stator 43 supported on the inner peripheral surface of the yoke 40 is rotatably supported at one end of a rotating shaft 45 by a ball bearing 46 provided at the bottom of the yoke 40 and at the other end. A ball bearing 47 provided on the holder 42 is rotatably supported. A brush 49 that is in sliding contact with a commutator 48 provided on the outer periphery of the rotating shaft 45 is supported on the inner surface of the bearing holder 42. The conducting wire 50 extending from the brush 49 is drawn to the outside through a grommet 51 provided in the first housing 31.

  As apparent from FIGS. 4 and 6, the speed reducer 37 is configured by connecting the first planetary gear mechanism 61 and the second planetary gear mechanism 62 in two stages. The first planetary gear mechanism 61 includes a ring gear 63 that is fitted and fixed to the opening of the second housing 32, a first sun gear 64 that is directly formed at the tip of the rotating shaft 45 of the motor 36, and a disk-like shape. The first carrier 65 and the first pinion pins 66, which are cantilevered by press-fitting into the first carrier 65, are rotatably supported via ball bearings 67, and simultaneously mesh with the ring gear 63 and the first sun gear 64. And four first pinions 68. The first planetary gear mechanism 61 decelerates and transmits the rotation of the first sun gear 64 that is an input member to the first carrier 65 that is an output member.

  The second planetary gear mechanism 62 of the speed reducer 37 includes a ring gear 63 common to the first planetary gear mechanism 61, a second sun gear 69 fixed to the center of the first carrier 65, a disc-shaped second carrier 70, and the like. Four second pinion pins 71, which are cantilevered by press-fitting into the second carrier 70, are rotatably supported via slide bushes 72, and simultaneously mesh with the ring gear 63 and the second sun gear 69. 2 pinions 73... The second planetary gear mechanism 62 decelerates and transmits the rotation of the second sun gear 69 that is an input member to the second carrier 70 that is an output member.

  Thus, by connecting the first and second planetary gear mechanisms 61 and 62 in series, a large reduction ratio can be obtained, and the reduction gear 37 can be downsized. Further, since the sun gear 64 of the first planetary gear mechanism 61 is formed directly on the rotating shaft 45 without being fixed to the rotating shaft 45 of the motor 36, the parts are compared with the case where the first sun gear 64 separate from the rotating shaft 45 is used. Not only can the number of points be reduced, but also the diameter of the first sun gear 64 can be minimized and the reduction ratio of the first planetary gear mechanism 61 can be set large.

  The second carrier 70 that is an output member of the speed reducer 37 is connected to a thrust receiving flange 74 that is an input member of the feed screw mechanism 39 via a coupling 38. The substantially disc-shaped thrust receiving flange 74 is supported rotatably by being sandwiched between a pair of thrust bearings 75 and 76 at the outer periphery thereof. That is, an annular lock nut 78 is fastened to the inner peripheral surface of the second housing 32 so as to sandwich the spacer collar 77, and one thrust bearing 75 is a thrust load between the second housing 32 and the thrust receiving flange 74. The other thrust bearing 76 is arranged to support the thrust load between the lock nut 78 and the thrust receiving flange 74.

  The coupling 38 includes two outer elastic bushes 79 and 79 made of, for example, polyacetal, and one inner elastic bush 80 made of, for example, silicon rubber, and each has eight on the outer periphery thereof. , 80a, and eight grooves 79b, 80b,... Protrude radially at equal intervals. On the other hand, on the opposing surfaces of the second carrier 70 and the thrust receiving flange 74, four claws 70a, 74a,... Protrude so as to face each other at equal intervals in the axial direction.

  The outer elastic bushes 79, 79 and the inner elastic bush 80 are overlapped so that the phases of the protrusions 79a, 80a,... Are aligned, and the second carrier 70 is placed in every other four of the eight grooves 79b, 80b,. Are engaged, and the remaining four of the eight grooves 79b, 80b are engaged with the four claws 74a of the thrust receiving flange 74.

  As is clear from FIG. 5, the first slide bearing 91 is fixed to the inner peripheral surface of the axially intermediate portion of the second housing 32, and the end member 93 that is screwed to the axial end portion of the first housing 32 is inside. A second slide bearing 92 is fixed to the peripheral surface, and the output rod 33 is slidably supported by the first and second slide bearings 91 and 92. The feed screw mechanism 39 that converts the rotational movement of the thrust receiving flange 74 into the thrust movement of the output rod 33 includes a male screw member 95 that passes through the center of the thrust receiving flange 74 and is fastened by a nut 94 (see FIG. 4). A female screw member 96 that is screwed onto the outer periphery of the male screw member 95 and is fitted to the inner peripheral surface of the hollow output rod 33 and fixed by a lock nut 97 is provided.

  As described above, since the output rod 33 is supported by the second housing 32 via the first and second slide bearings 91 and 92, the radial load applied to the output rod 33 is reliably supported by the second housing 32. The feed screw mechanism 39 can be prevented from being damaged.

  The male screw member 95 and the female screw member 96 of the feed screw mechanism 39 are constituted by a multi-thread screw (fast screw) having a plurality of threads (four threads in the embodiment). The stroke S when the rotation is 360 ° is equal to the length of one pitch of the thread multiplied by the number of threads (in the embodiment, four pitches of the thread).

  A stroke sensor 102 provided for detecting the stroke position of the output rod 33 and feeding it back to the control device when the toe control actuator 14 is expanded and contracted is a thrust receiving flange integrated with the male screw member 95 of the feed screw mechanism 39. The resolver is configured to detect 74 rotational positions. That is, the stroke sensor 102 includes a detected portion 104 made of a plurality of permanent magnets fixed to the outer peripheral surface of the thrust receiving flange 74 at predetermined intervals, and a coil that magnetically detects the position of the detected portion 104. And a sensor main body 106 that houses the detection unit 105. The sensor body 106 is fixed to the second housing 32 so that the detection unit 105 faces the detected parts 104 through an opening 77a formed in the spacer collar 77 and an opening 32d formed in the second housing 32. The

  As is apparent from FIG. 4, a contraction side stopper 98 made of a circlip on the inner peripheral surface of the second housing 32 close to the thrust receiving flange 74 is attached, and the abutting portion of the output rod 33 is attached to the contraction side stopper 98. 33c opposes so that contact is possible. Further, as is apparent from FIG. 5, an extension side stopper 99 made of a circlip is mounted on the outer peripheral surface of the output rod 33, and the abutting portion 93 a of the end member 93 is opposed to the extension side stopper 99. To do.

  The stroke of the output rod 33 from the contracted end where the contraction side stopper 98 contacts the abutting portion 33c of the output rod 33 to the extension end where the extension side stopper 99 contacts the abutting portion 93a of the end member 93 is the stroke S. It is set slightly smaller than (4 pitches of thread). Therefore, the rotation angle of the male screw member 95 while the output rod 33 moves by the stroke S is less than 360 °.

  In order to prevent water and dust from entering the gap between the second housing 32 and the output rod 33, the boot 108 is inserted into the annular step 32 c formed in the second housing 32 and the annular groove 33 a formed in the output rod 33. The both ends are fitted and fixed by bands 109 and 110, respectively.

  When the output rod 33 extends, the volume of the internal space of the first and second housings 31 and 32 increases, and conversely, when the output rod 33 contracts, the volume of the internal space of the first and second housings 31 and 32 decreases. The pressure in the internal space may fluctuate and hinder the smooth operation of the toe control actuator 14. However, since the internal space of the hollow output rod 33 and the internal space of the boot 108 communicate with each other through the vent hole 33 b formed in the output rod 33, the pressure fluctuation is reduced by the deformation of the boot 108. The toe control actuator 14 can be smoothly operated.

  When the toe control actuator 14 is controlled to expand and contract, the stroke sensor 102 detects the stroke position of the output rod 33 and feeds it back to the control device. That is, when the thrust receiving flange 74 integral with the male screw member 95 of the feed screw mechanism 29 rotates, the stroke sensor 102 causes the second housing 32 to detect the detected portion 104 made of a permanent magnet fixed to the outer peripheral surface of the thrust receiving flange 74. The rotation angle of the male screw member 95 is detected by the detection unit 105 of the sensor main body 106 fixed to. Since the rotation angle of the male screw member 95 has a one-to-one correspondence with the stroke of the output rod 33, the stroke position of the output rod 33 can be known from the rotation angle of the male screw member 95.

  If the detected rotation angle α ° and 360 ° + α ° of the male screw member 95 is to be identified by the stroke sensor 102 made of a resolver, special logic is required. However, since the rotation angle of the male screw member 95 (that is, the thrust receiving flange 74) is limited to less than 360 ° by the contraction side stopper 98 and the extension side stopper 99, the stroke position of the output rod 33 is not required. Can be known. Moreover, since a multi-thread screw is used for the feed screw mechanism 39, a sufficient stroke amount can be given to the output rod 33 even if the rotation angle of the male screw member 95 is limited to less than 360 °.

  As described above, since the detected portions 104... And the detecting portions 105 of the stroke sensor 102 are arranged inside and outside in the radial direction, the axial dimension of the stroke sensor 102 can be shortened as compared with those arranged in the axial direction. Further, the detected portion 104 provided on the thrust receiving flange 74 integral with the male screw member 95 only moves in the circumferential direction and does not move in the axial direction. Therefore, the axial dimension of the detecting portion 105 is shortened. The axial dimension of the stroke sensor 102 can be shortened, thereby contributing to the downsizing of the toe control actuator 14.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various design changes can be made without departing from the present invention described in the claims. Is possible.

  For example, in the embodiment, the male screw member 95 is connected to the motor 36 side and the female screw member 96 is connected to the output rod 33 side. However, the relationship is reversed, and the female screw member 96 is connected to the motor 36 side and output. A male screw member 95 may be connected to the rod 33 side.

  The telescopic actuator of the present invention is not limited to the toe control actuator 14 of the embodiment, and can be applied to any application.

Perspective view of left rear wheel suspension device 2 direction view of FIG. 3-3 enlarged sectional view of FIG. 4 enlarged view of FIG. 5 enlarged view of FIG. Exploded perspective view of reducer and coupling

Explanation of symbols

32 Second housing (housing)
33 Output rod 36 Motor 39 Feed screw mechanism 45 Rotating shaft 74 Thrust receiving flange 95 Male screw member (first screw member)
96 Female thread member (second thread member)
102 Stroke sensor 104 Detected part 105 Detecting part

Claims (2)

A feed screw mechanism (39) including a first screw member (95) and a second screw member (96) screwed to each other is provided, and the first screw member (95) is connected to a rotating shaft (45) of a motor (36). And the second screw member (56) is connected to the output rod (33), and the stroke position of the output rod (33) due to the rotation of the rotating shaft (45) of the motor (36) is determined by a stroke sensor (102). ) In the telescopic actuator detected by
The rotation angle of the first screw member (95) is set to less than 360 °, and the stroke sensor (102) determines the stroke position of the output rod (33) based on the rotation angle of the first screw member (95). A telescopic actuator characterized by detecting.   The first screw member (95) includes a thrust receiving flange (74) for transmitting axial thrust force to the housing (32), and the stroke sensor (102) is provided on an outer periphery of the thrust receiving flange (74). The telescopic actuator according to claim 1, further comprising: a detected portion (104); and a detecting portion (105) provided in the housing (32) and facing the detected portion (104). .

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